How Well are the World’s Rivers Protected?

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To what extent are the world’s rivers protected?

In 2010, the Convention on Biological Diversity (CBD) set a 17 percent target for the protection of ‘inland waters,’ including rivers. Given that freshwater systems are widely acknowledged to be among the most threatened systems worldwide, it was an accomplishment for countries to commit to a global conservation target for them. But there was a problem: there was no good way to measure progress toward that target.

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That situation is changing. Now, using a high-resolution dataset of the world’s rivers called HydroSHEDS, we can finally begin to assess protection levels for these systems virtually anywhere on Earth. A new study, co-authored by freshwater scientists from the Conservancy, McGill University, WWF, and Griffith University, uses this dataset for a first-ever global gap assessment of the world’s rivers. The results not only suggest whether, and where, rivers may lack protection, but the study also introduces an approach that takes gap assessments of protection to a new level.

Gap assessments have typically looked only at immediate, or ‘local’ protection – that is, the protection that a designated protected area (PA) may offer to the systems occurring within it. This approach has generally been considered adequate, if not perfect, for terrestrial systems like forests or grasslands. We know, however, that inland water systems sit at the lowest points on any landscape and are subject to threats originating upstream and upland in their catchments. A river reach, then, may receive local protection where it flows through a protected area, but that local protection may be unable to mitigate impacts originating upstream.

As an illustration, imagine a headwater area where mining activity is discharging toxic pollution into a nearby stream. That pollution finds its way into a downstream river reach that flows through a well-protected reserve. Can we call that river reach protected if its aquatic species are being poisoned from toxins derived upstream?

For every river reach worldwide, the new approach outlined in the study applies a measure of ‘integrated’ protection, combining local and upstream protection and using a kind of sliding scale for sufficiency. Small headwater catchments might be expected to achieve nearly complete protected area coverage, while at the other end of the spectrum the world’s largest rivers with massive upstream catchments are considered to have sufficient upstream protection at lower levels.

The study finds that most river systems around the world fall far short of the 17 percent CBD target, both for local protection and especially for integrated protection. Fully 70 percent of river reaches, by length, have no protected areas in their upstream catchments, and only 11 percent of river reaches (again by length) achieve integrated protection. Levels of protection vary widely by region; South America, dominated by the well-protected Amazon, has average local and integrated levels approaching 30 percent, whereas both levels are under 10% for the Middle East. Levels also vary within individual basins for different river size classes.

These findings help to highlight where there are worrying protection gaps for rivers, putting aside functional gaps arising from poor PA management and ‘false’ gaps where landscapes and rivers receive de facto protection outside formal PAs. The study adds to ongoing conversations, collected in a recent supplement to the journal Aquatic Conservation, about how PAs can best be leveraged to benefit freshwater species and systems. Equally important, the study contributes to stimulating discussion about how we measure protection, not only for rivers but for all systems, given the preponderance of external threats impinging on PAs.